THE STEM 107 
or stem that has its roots established in the ground. 
The important thing in both cases is to have the 
ecambium layer of bud or scion in contact with that of 
the stock and to exclude all air carefully from the 
point of junction. By this means new plants exactly 
hke that which produced the bud or scion may be 
obtained, in which respect vegetative differs from 
seed reproduction. In the latter, for instance, seedlings 
raised from stones derived from the choicest peaches 
and cherries may give rise to but worthless varieties. 
Roots AND STEMS. 
Both roots and stems have epidermis, cortex and 
stele. In roots, the growing point is protected by a 
root-eap, in stems by a sheath of leaves. In roots, wood 
and bast are separate, being arranged alternately; in 
stems they are united in vascular bundles. Stems 
have nodes and internodes, and roots have not. Root 
branches originate from the stele, while stem branches 
spring from the cortex. Roots are, as a rule, positively 
sveotropie and hydrotropic, and negatively heliotropie, 
while stems are positively heliotropie and negatively 
geotropic and hydrotropic. Stems bear leaf buds, 
while roots, as a rule, do not. Root hairs, too, are an 
entirely different thing, and perform a different work, 
from the hairs of stems and leaves. 
RESERVE MATERIALS. 
Reserve materials are always found in seeds, but 
in some plants they accumuiate also in the stems, 
roots or leaves. Since the topic has already been, and 
will again be discussed, it may be well to give a brief 
summary, and this summary, if all tests be duly made, 
will give all the assistance required. It may be men- 
tioned as a preliminary, that, in testing for starch and 
sugar, it is best to add the iodine first. Then, whether 
starch is present or not, the Fehling’s solution may be 
